1. Field of the Invention
The present invention relates generally to air conditioning systems and more particularly to an air conditioning system which uses a static desiccant core for humidity control and/or dehumidification.
2. The Background of the Invention
Air conditioning systems for cooling air in an enclosed space typically must condense water vapor from an air stream to achieve adequate dehumidification. The result is that the air conditioning system works to maintain temperature control in the space (sensible load) and also must have the capacity to remove the heat of condensation from the water vapor which is extracted from the air stream to maintain the desired level of humidity in the enclosed space (latent load).
It has frequently been found that with previously proposed air conditioning systems the temperature required to condense water vapor in order to maintain the desired humidity in an enclosure is lower than the temperature needed to be maintained within the space itself. Accordingly, it is often necessary to reheat the dehumidified air in order to maintain desired comfort levels. In addition, contemporary indoor air quality requirements have created a demand for large quantities of outside air to be supplied continuously to the enclosed space. This typically means that a greater load is placed on the air conditioning system than was required in the past, making the initial size or capacity of the air conditioning unit greater with attending increased capital and operating costs.
To avoid these excess expenses, air conditioning systems using rotary enthalpy wheels have been previously proposed. Such systems generally reduce the load imposed by outside air on the air conditioning unit by utilizing exhaust air from the enclosed space as a driving force for temperature and moisture transfer from the make-up air to the rotary wheel and then finally to the exhaust air discharge. Such systems have not been found to be satisfactory in practice because of cross-contamination between air streams and because of the complexity of the system. As a result these systems have a poor reputation for reliability and suffer from bearing, drive system and metal fatigue.
In accordance with the present invention an air conditioning system is disclosed in which the return air in the enclosure is exhausted into the atmosphere, but is used first in the process in order to treat outside air being introduced into the enclosure for air exchange purposes. The return air is passed in counter current relationship to the outside air in a fixed desiccant core unit having no moving parts.
It is an object of the present invention to provide an improved air conditioning system based upon desiccant technology.
Another object of the present invention is to provide an improved air conditioning system which is less expensive to construct and to operate as compared to prior art systems.
Yet another object of the present invention is to provide a desiccant based air conditioning system which has greater mechanical reliability and lower risk of cross circuit air contamination due to leakage.
A still further object of the invention is to provide a desiccant based air conditioning system which allows for independent control of temperature and humidity.